1. Field of the Invention
This invention relates generally to the field of telephony systems. More particularly, the invention relates to a system for coordinating among multiple telephony communication channels.
2. Description of the Related Art
For many years, the “Plain Old Telephone Service” or “POTS” (also referred to as the “Public Switched Telephone Network” or “PSTN”) offered by AT&T and later the “baby bells,” was the only telephone service available to the consumer. With the rapid advances in digital communications technology over the past several years, however, consumers now have a variety of choices for telephone services in lieu of, or in addition to, POTS.
IP telephony service, for example, is becoming an increasingly popular alternative to POTS. As its name suggests, IP telephony refers to the two-way transmission of audio over a packet-switched TCP/IP network. It is also commonly referred to as “Voice Over IP,” or “VoIP.” Today, users typically sign up for IP telephony service through their local cable companies. However, in the future, the IP telephony service may be offered by various Internet Service Providers (“ISPs”).
There are several advantages to IP telephony over POTS. For example, packet networks are more scalable than traditional circuit-switched telephone to networks, and they naturally integrate with all Internet-based applications. Although the backbone of the telephone network has been converted to digital for some time, the circuit-switched nature of the PSTN is wasteful. Even though one person talks and the other listens, both the incoming and the outgoing channels are dedicated for the duration of the conversation. In addition, newer audio codecs reduce the required bitrate from the traditional 64 Kbps (i.e., with PCM) down to 8 Kbps and below, while maintaining the same level of quality. As a result, the digital bandwidth for voice over IP may be less than 1/16th that of the POTS.
One major problem with current IP telephony systems, however, is that the IP telephony device at the user's home (often a computer) must be powered in order to operate. As such, current IP telephony systems are incapable of providing a “lifeline” service, i.e., one which will be available to users at all times, even when power outages occur. Users must therefore subscribe to the basic “primary line service” offered by their local telephone company in addition to the IP telephony service. Currently, however, there are no systems capable of coordinating between the two different telephony services.